:root{--brand: #ed5919;--orange: #f77a20;--yellow: #ffc62f;--green: #526841;--brown: #533a28;--ink: #302b25;--muted: #6c6359;--paper: #fffcf6;--line: #e9e0d3;--gradient: linear-gradient(115deg, #ed5919 0%, #ffbf28 44%, #82934e 74%, #62452e 100%)}*{box-sizing:border-box}body{margin:0;font-family:Segoe UI,system-ui,-apple-system,sans-serif;background:var(--paper);color:var(--ink)}.app{min-height:100vh;display:flex;flex-direction:column}.site-header{background:var(--gradient);color:#fff;text-align:center;padding:2.2rem 1rem 1.8rem}.site-header h1{margin:0;font-size:2.4rem;letter-spacing:.02em}.subtitle{margin:.4rem 0 0;opacity:.95}main{flex:1;width:min(980px,94vw);margin:1.5rem auto}.tabs{display:flex;gap:.5rem;margin-bottom:1rem}.tab{border:1px solid var(--line);background:#fff;color:var(--muted);padding:.55rem 1.1rem;border-radius:8px 8px 0 0;cursor:pointer;font-size:.95rem}.tab.active{background:var(--brand);border-color:var(--brand);color:#fff;font-weight:600}.panel.hidden{display:none}.panel{background:#fff;border:1px solid var(--line);border-radius:10px;padding:1.2rem 1.4rem;margin-bottom:1.2rem}.field{display:block;margin-bottom:.9rem;font-size:.95rem}.field select,.field input[type=number],.formula-editor input,.formula-editor textarea{display:block;width:100%;margin-top:.3rem;padding:.5rem .6rem;border:1px solid var(--line);border-radius:6px;background:var(--paper);color:var(--ink);font-size:.95rem}.field.checkbox{display:flex;align-items:center;gap:.5rem}.field.checkbox input{width:auto}input[type=range]{width:100%;accent-color:var(--brand)}.harmonics-number{width:6.5rem;margin-top:.4rem}input[type=checkbox]{accent-color:var(--brand)}.formula-display{background:var(--paper);border:1px dashed var(--line);border-radius:8px;padding:.6rem 1rem;margin-bottom:1rem;overflow-x:auto}.description{color:var(--muted);font-size:.9rem;margin:.4rem 0 0}.approx-error{color:var(--brown);font-size:.9rem;margin:.5rem 0 0;font-weight:600}.approx-error small{font-weight:400;color:var(--muted)}.about h2{color:var(--brown);margin-top:0}.about h3{color:var(--brown);margin:1.2rem 0 .4rem}.about code{background:var(--paper);border:1px solid var(--line);border-radius:4px;padding:0 .3rem;font-size:.9em}.about li{margin-bottom:.7rem}.controls{display:flex;flex-wrap:wrap;gap:1.2rem;align-items:center}.controls .field{flex:1 1 260px;margin-bottom:0}.canvas-wrap{background:#fff;border:1px solid var(--line);border-radius:10px;padding:.6rem}.fourier-canvas{width:100%;height:440px;display:block}.formula-editor h3{margin-top:0;color:var(--brown)}.formula-editor label{display:block;margin-bottom:.8rem;font-size:.95rem}.formula-editor fieldset{border:1px solid var(--line);border-radius:8px;margin-bottom:.8rem}.formula-editor legend{font-size:.85rem;color:var(--muted)}.coef-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:.7rem}.latex-preview{background:var(--paper);border:1px dashed var(--line);border-radius:8px;padding:.4rem .8rem;margin-bottom:.8rem;min-height:2.4rem;overflow-x:auto}.formula-editor button[type=submit]{background:var(--brand);color:#fff;border:none;border-radius:6px;padding:.6rem 1.4rem;font-size:1rem;cursor:pointer}.formula-editor button[type=submit]:hover{background:var(--orange)}.form-error{color:#b7410e;font-size:.9rem}.form-ok{color:var(--green);font-size:.9rem}.hint{font-size:.85rem;color:var(--muted);margin-top:.8rem}button.danger{background:none;border:1px solid #b7410e;color:#b7410e;border-radius:6px;padding:.4rem .9rem;cursor:pointer}a{color:var(--brand)}.site-footer{margin-top:auto}.footer-gradient{height:6px;background:var(--gradient)}.footer-content{background:var(--brown);color:#f7efdf;text-align:center;padding:1.6rem 1rem 2rem;font-size:.92rem}.footer-brand{font-size:1.15rem;font-weight:700;color:var(--yellow);margin:0 0 .5rem}.footer-content a{color:#ffcb60}.footer-license{font-size:.8rem;opacity:.8;margin-top:.8rem}